ast: Add PointerVisitor

gcc/rust/ChangeLog:

	* Make-lang.in: Compile it.
	* ast/rust-builtin-ast-nodes.h: Add missing methods for getting pointers.
	* ast/rust-expr.h: Likewise.
	* ast/rust-item.h: Likewise.
	* ast/rust-path.h: Likewise.
	* ast/rust-pattern.h: Likewise.
	* ast/rust-type.h: Likewise.
	* ast/rust-ast-pointer-visitor.cc: New file.
	* ast/rust-ast-pointer-visitor.h: New file.

Author: CohenArthur

gcc/rust/Make-lang.in

@@ -84,6 +84,7 @@ GRS_OBJS = \
     rust/rust-ast-dump.o \
     rust/rust-ast-collector.o \
     rust/rust-ast-visitor.o \
+    rust/rust-ast-pointer-visitor.o \
     rust/rust-hir-visitor.o \
     rust/rust-hir-dump.o \
     rust/rust-session-manager.o \